Electron tube



June 15, 1937.

P. G. WEILLER 2,084,172

ELECTRON TUBE Filed Dec. 15, 1930 VINVENTOR Pau/ G. Wed/er Y ATTORNEY Patented June 15, 1937 UNi'iED STATES 2,084,172 ELECTRON TUBE Paul G. Weiller, Bloomfield,

niesne assignments, to

N. 3., assignor, by Radio Corporation in America, a corporation of Delaware Application December 13,

10 Claims.

My invention relates to electron tubes and more particularly to novel apparatus for and methods of cathode construction therefor.

It has been proposed that indirectly heated cathodes be made of provide large electron e a hollow construction to mission surface. In these cathode structures, the heating filament 1S surrounded by a metallic sheath and insulated therefrom. side and the The metallic sheath entire unit reflecting screen, the space and the cathode being filled is coated on the outthen enveloped by a between the screen with coated material to increase the emitting surface without increasing the heat With the power purposes, such efficiency of operation radiating surface. development of as large rectifying tubes,

gaseous tubes for play a more and more important part in the tube, and it is accordingly of importance, where large values are involved, to operate degree of efficiency.

to my invention, the heating element highest possible According current the tube at the and envelopes within itself the whole structure including the emitcathode. a hollow trough or understood that any other shape may electron emitter surface of the open trough, a very surface is provided. The filament or Inasmuch as the is on the inner large emitting heating portion is integral with and a part of the entire accordingly very efficient heating is obtained since all of the heat generated trough reducing heat radiation over the emitwhich constitutes a serious cause of inefficiency of the cathode con truction heretofore used.

An object of my invention is to provide a novel cathode construction which will operate at a with a maintenance of temperature equal to that of directly heated cathodes.

Still a further object vide a novel cathode power tubes convenient methods of Other objects of my of my invention is to proconstruction suitable for and adapted for inexpensive and manufacture.

invention will be clearer.

1930, Serial No. 502,035

from the detailed description of the invention which is to follow.

Referring to the drawing:

Figure l is a perspective view of my novel cathode construction.

Figure 2 is a perspective view of a of the cathode shown in Figure l.

Figures 3, 4:, 5 and 6 are diagrammatic showings of connections from the heating filament to the cathode.

Figure I is emitter.

Figure 8 discloses a radio tube embodying my novel cathode construction.

As shown, the cathode l is of the hollow construction preferably in the form of a trough having an opening 2 through which, as will appear hereinafter, the generated electrons from the emitter are permitted to escape to the anode of the tube. Conductors 3 and i for carrying the heating current, are connected to the heating element 5 which may be of any well known bright nickel, suitable for electrical heating purposes and which is an integral part of and covers the entire cathode construction I. heater may be easily stamped to shape from sheet material and thereafter conveniently assembled.

On the inner surface of the heating element there is placed an emitting coating 5 of any well known composition and connected to the terminal 6 extending to the external electrical circuits as shown in detail in Figure 8. This emitter may be first formed by coating a core comprising a series of strips of material I in parallel and at right angles to each other as shown in Figure "1. After the material is coated, it is inserted in the inner surface of the hollow trough.

The outer surface of the core heating material is polished to form a mirror-like appearance, thus reducing heat radiation over this very large surface.

As shown in detail in Figures 3, land 5, th cathode need not necessarily be connected to the filament throughout its length. As shown in Figure 3, only one end of the emitter is confilament, as at point 9 the emitter is completely insulated from the heating filament, in Figure 5 two emitters are provided, one end of each of which is connected to opposite ends of the heating filament and in Figure 6, the emitter is connected modified form a diagrammatic showing of my 'at its midpoint to the midpoint of the heater.

connected to opposite terminals of the source. ature.

passes through its positive and negative cycles. and means for heating said emitter to electron As Will be understood, with these constructions, emitting temperature. an indirectly heated equipotential cathode con- 7. A cathode structure for an electron disstruction is obtained. charge tube comprising an elongated tubular I claim: body having a lengthwise slot formed by the (11S 15 with emitting material therein, said hollow closely spaced relation such that the width of 2. A hollow cathode comprising a troughcoating to electron emitting temperature.

therethrough to maintain said emitting layer at operative relation to said cathode.

electron emitting temperature. A discharge device comprising a vessel, a cyto its inner surface, and electrical leads to the electron emissive surface, and at least one anode to an electron emitting temperature said cathode serving as a heater therefor, and an 5. A cathode comprising a hollow metallic cyanode in cooperative relation to said cathode. lindrica1 body having a lengthwise slot and a PAUL G. WEILLER. 

